Carbon Dioxide Zero-Emission Hydrogen System based on Nuclear Power

Transcription

1 Carbon Dioxide Zero-Emission Hydrogen System based on Nuclear Power Yukitaka Kato Research Laboratory for Nuclear Reactors Tokyo Institute of Technology Paper #51, 2B2 Innovative Energy Transmutation COE-INES International Symposium, INES-1 1 November, 2004, Tokyo, Japan 1

2 Contents Back ground: Hydrogen supply for fuel cell vehicles CO 2 zero-emission hydrogen career system using a regenerative reformer Experimental demonstration Evaluation of the hydrogen career system 2

3 Hydrogen for FC -A fuel cell is environmental friendly?- Problems of supply to a conventional fuel cell vehicle Compressed fuel : high-energy consumptions for production and pressurization, and explosiveness 1 st Energy input 2 nd Energy input Explosiveness of Hydrogen source Compressed cylinder Fuel cell O Fig. Subjects for hydrogen supply to a fuel cell vehicle 3

4 Fuel reforming for hydrogen supply to a fuel cell vehicle Problems of supply to a conventional fuel cell vehicle Fuel Reforming: complex structure, and CO 2 emission Heat input Heat output CH 4 Cat. Cat. O Reformer Shift Converter CO 2, Fuel cell CO 2, O Fig. Conventional reforming system for a FC vehicle 4

5 Regenerative Reforming -Use of chemical absorption- Fuel reforming for methane CH 4 + O 3 +CO, H 1 = kj/mol CO+ O +CO 2, H 2 = 41.1kJ/mol CaO carbonation CaO(s)+CO 2 (g) CaCO 3 (s), H 3 = kj/mol Regenerative reforming (CO 2 absorption reforming, self-heating) CaO(s)+CH 4 (g)+2 O(g) 4 (g)+caco 3 (s), H 4 = 13.3 kj/mol 5

6 Non-equilibrium reaction for hydrogen production Based on fuel reforming Separation processes for non-equilibrium reforming Separating CO 2 from system using chemical absorption Merit of non-equilibrium reforming Enhancement of hydrogen production Use of exothermic reaction heat for endothermic reforming Drop in reforming temperature CH4 steam reforming: 700 o C -> 500 o C Enhancement of high-carbon numbers reactant reforming Kerosene, C 2 H 5 OH and higher hydrocarbon Reuse of carbon dioxide CO 2 zero-emission system Link with nuclear power system 6

7 CO 2 zero-emission FC vehicle using the regenerative reformer Regenerative reforming CO 2 recoverable, self heating, and simple reforming system thermally regenerative CO 2 zero-emission FC vehicle Safety carrier system under low-pressure and high-density (1) CO 2 absorption reforming CH 4 O CaO, Cat. CO 2 absorption reforming (2) CaO regeneration/co 2 recovery Surplus heat/electricity for thermal decarbonation Fuel cell O CaCO, Cat. CO 2 CO 2 recycle process 7

8 CO 2 zero-emission hydrogen career system Hydrogen system driven by surplus electricity and heat from nuclear power plants, and unstable energy. Safe and compact hydrogen transportation CO 2 zero emission energy system Fuel cell vehicles Recycle Renewable energy system Electricity/ Heat CO 2 HTGR Electrolysis of water Hydrogenation CaO CO 2 CH 4 regenerator storage regenerator Regeneration Station Electricity from nuclear power plants Heat from hightemperature gas reactor(htgr) and H. T. industries CH 4 8

9 Experiment of the regenerative reformer Demonstration of the possibility of the regenerative reforming system For polymer electrolyte fuel cell (PEFC) operated at a hydrogen pressure of less 0.3 MPa. (1) CO 2 (2) (8) (9) (10) A quartz tube, 15 mm in inner diameter and an effective heating zone length of 600 mm. CH 4 (12) (3) (5) (6) (7) (11) Ar (4) (1) flow meter, (2) evaporator, (3) micro-feeder, (4) water reservoir, (5) electric furnace, (6) reactor tube, (7) reactor bed, (8) thermocouple, (9) furnace heating controller, (10) liquid-gas separator, (11) gas chromatograph, (12) soap flow meter 9

10 CO 2 absorption reforming During the initial 60 min, hydrogen production was higher than the equilibrium concentration of conventional reforming. Charged CaO absorbed well CO 2 by carbonation. CO 2 <1% CO was removed, <1% Low-temperature reforming (conventional reform. temp. > 700 o C) c [mol%] Equilibrium concentration of the conventional reforming CH t [min] Equilibrium concentration of the regenerative reforming T=550 o C CO 2 CO Al 2 O 3 Ni cat+cao Fig. Temporal change of effluent composition of the regenerative (a) regenerative reformer (RGR) reformer at 550 C 10

11 CO 2 removal from reforming gas 20 Measured Equilibrium Effluent CO 2 concentration from RGR at 550 C was less than 1%. c CO2 [mol%] RGR SQR CVR T [ o C] Fig. Effect of bed temperature on effluent carbon dioxide concentration of the reformer comparing with other type reformers. 11

12 productivity 94% of production was measured by the RGR at 550 C. c H2 [mol%] Measured Equilibrium RGR SQR CVR T [ o C] Effect of bed temperature on hydrogen production concentration of the reformers. 12

13 Estimation of a zero emission vehicle 1 kg of in order to drive for 100 km 7.46 kg (9.04 liters) of CaO was required for the RGR. 13

14 Comparison between systems Table: Scale of energy storage facilities for 100 km mileage, 14.7 kwh, 500 mol- (= Petroleum of 4 L, 2.8 kg) 25.6 L Hydrogen cylinder, 70 Mpa mass [kg] volume [liter] Matal hydride, 1.5 wt% Advanced Li-ion battery Advanced lead-acid battery Regenerative reformer 67 kg 100 kg 400 kg 9.6 kg 7.9 L volume [liter], mass [kg] 14

15 Estimation of the zero-emission hydrogen career system Nighttime surplus electricity of 1 GW for 8 hours was used for the regeneration at the regeneration stations. The RGR packages of 1.3 million pieces/day are able to be regenerated in the stations. CO 2 of ton/day is expected to be recovered from the stations. 15

16 Conclusions The regenerative reformer was applicable to a practical CO 2 zero-emission reforming with safety hydrogen supply. The required amount of CaO for the reformer was expected to be small enough comparing with other hydrogen storage system or batteries. The system can utilize surplus electricity generated from renewable energy system and nuclear power plant. Electricity of 1 GW for 8 h can regenerate 1.3 million of reforming packages, and recover 7.1 ton of CO 2. The hydrogen career system using the regenerative reformer would widen need of those power plants because the system realizes new vehicle system of total CO 2 zero-emission. The hydrogen career system also contributes to load leveling of power plant operation. 16

17 Shifting into non-equilibrium by separation Reforming processes (a) Conventional, non-treatment Reforming, CO 2, CO, others C n H m O k +b O hydrogen source (b) separation Reforming+ separation Nom-equilibrium Equilibrium mixture Pure Exhaust CO 2 Fuel cell (c) CO 2 separation Reforming+CO 2 separation Pure Nom-equilibrium CO 2 fixation 17

18 Unstable Operation -Load leveling for Economical Plant Operation- Load change and unstable operation Low-annual operation rate Uneconomic Load leveling for 100% operation Energy storage Energy conversion Unstable & Uneconomical Region Fig. A daily load change in a summer day in Japan Tokyo Electric Power Co. Peak Electric Load (2001) Japan=181 GW Tokyo area=64 GW (24 Jul.), 51 GW (15 Jan.) 18

19 Diversification of energy supply and demand Supply Demand Present Stable Stable Future Diversified Storage Instable Decentralization/ Daily and Renewable energy Seasonal change Fig. Forecast of the change of energy flow pattern Future society needs high-efficient tech. of, Energy storage Energy transportation Use of chemical Energy conversion reaction 19

20 25 Pre-breakthrough Post-breakthrough c i [mol%] CH 4 CO 2 CO c H2 [mol%] 5 T=550 o C f CH4 =106Nml/min t [min] 20 20

21 o C pre 550 o C pre 600 o C pre 500 o C post 550 o C post 600 o C post CO CH 4 CO 2 f CH4 =106Nml/min c [mol%]